The activation energy by definition, is the minimum energy (or threshold energy) required for two particles of reactants upon collision to form products. Show The Arrhenius equation could also be written as:#k=Ae^(-(Ea)/(RT))#, where,#A=zp#is the Arrhenius factor. Taking the natural logarithm of both parties, we get: #lnk=-(Ea)/R(1/T)+lnA# Assuming that#A#is independent of temperature, when#T#is increased, the equilibrium constant#k#will also increase and therefore, the rate of the reaction will also increase . Chemical reactions are everywhere around you and inside you. In addition to the biochemical reactions that allow you to transform the molecules you eat and breathe into usable energy, there are industrial laboratories in cities around the world producing chemicals as well as products that rely on chemicals for their manufacture. One of the most important aspects of a reaction, in addition to the product or products produced and having a proper supply of reactants, is how quickly a reaction can be expected to proceed. This can have an impact on safety, product quality and other outcomes. One of the factors affecting reaction rates that can be changed with ease in most cases in the lab is temperature. The effect of temperature on rate of reaction can have a tremendous impact. Think for a moment about how temperature might be expected to impact reaction rates, and read on for more insight about the various things that can speed up or slow down chemical reactions. What Factors Affect Reaction Rates?The effect of temperature on rate of reaction is just one of the things that can affect how a reaction proceeds, that is, how quickly whatever reactants are present become transformed into products. Of course, many of these factors are active at all times and can have competing influences on the overall rate of a given reaction.
The Effect of Temperature on Rate of ReactionAs a rule of thumb, a rise in temperature of 10 °C doubles the reaction rate. Why might increasing the temperature alter the rate of a chemical reaction? If you're thinking it's because the molecules involved are moving more quickly when the temperature is higher, you're on the right track. Temperature is actually a measure of the average kinetic energy of molecules in motion. Molecules in motion tend to stay in motion until they encounter an external force, and when different reactant molecules are mixed together, they have little to run into besides each other. When temperature increases, the amount of atomic or molecular collisions between molecules increases. But the change in reaction rate with temperature is not just a function of the temperature; instead, temperature increases actually affect the rate constants (written k) of reactions in a predictable way. What Is the Collision Theory of Reaction Rates?When molecules collide, they can do a number of things. The same is true of any two objects encountering each other in the real world. If you drove blindly though a parking lot trying to fit your car at random into parking spaces without looking at the lines on the pavement, you would have a relatively small chance of success of lining the vehicle up properly. But if you did this more quickly, you would have more total successes even if your error rate stayed the same. This is sort of what happens when reactant molecules collide. They need to collide in order to be close enough together to interact, but while this condition is necessary, it is not sufficient. The molecules must also be in an optimal orientation in space to trigger a reaction. In the end, the effect of temperature on reaction rate is determined through its effect on the rate constant k, which in turn depends on the activation energy Ea of the reaction in question. Higher temperatures will see a higher fraction of molecules attain this minimum kinetic energy needed to get the reaction started. Related ArticlesWhat is Chemical Equilibrium?What Factors Influence the Rate of a Chemical Reaction?Four Ways to Speed Up a Chemical ReactionHow to Measure the Optimum Temperature for an EnzymeName One Way to Decrease the Rate of SolvationHow Does Concentration Affect the Rate of Reaction?What Happens to Chemical Bonds During Chemical ReactionsWhat Effect Does Temperature Have on the Process of...What Happens to a Boiling Temperature as Pressure Decreases?How Enzyme Activity Changes as Enzyme Concentration...Does the Mass of the Reactants Affect the Rate of Chemical...Science Project: The Effects of Temperature on LiquidsDifferent Types of CatalystsWhat Role Does Heat Play in Chemical Reactions?Density Vs. ConcentrationHow to Calculate Volume ChangeFive Factors That Affect Reaction RatesWhat Does a Catalyst Do in a Chemical Reaction?References
About the Author Kevin Beck holds a bachelor's degree in physics with minors in math and chemistry from the University of Vermont. Formerly with ScienceBlogs.com and the editor of "Run Strong," he has written for Runner's World, Men's Fitness, Competitor, and a variety of other publications. More about Kevin and links to his professional work can be found at www.kemibe.com. |